The amount of information to be handled by devices such as servers or routers is rapidly increasing along with popularization of the Internet and the like. The transmission capacity of signals communicated between semiconductor parts such as LSIs in those devices is expected to continue to grow quickly. On the other hand, problems such as increased power consumption, delayed signal transmission, lowered reliability of signal lines, and signal interference are becoming serious in the conventional electric wiring technology. In order to solve those problems, application of optical wiring is being examined for various transmission distances from a long-distance transmission to a short-distance transmission between chips or within a chip.
Optical receiver circuits that are highly sensitive, are small in size, and consume low electric power are important in optical information transmission. As disclosed in Patent Literature 1 and Patent Literature 2, there has been proposed an optical receiver circuit in which capacitors for AC (alternate current) coupling are connected to an anode and a cathode of one light-receiving element to generate a set of signal currents in two signal lines and output it to a subsequent TIA (transimpedance amplifier) circuit. With the AC coupling, a bias voltage of the light-receiving element can be determined independently of the TIA circuit. Furthermore, DC components can be removed to extract only signal components. Non-Patent Literature 1 discloses an optical receiver circuit in which two light-receiving elements are connected to a subsequent TIA circuit via respective AC coupling capacitors.